Evaluation of Adhesion Properties in Bitumen-Aggregate Systems for Winter Surfacing Seals Using ...

189 Pages·2014·10.84 MB·English

Evaluation of Adhesion Properties in Bitumen-Aggregate

Systems for Winter Surfacing Seals Using the Bitumen
Bond Strength Test

By
Emmanuel Twagirimana

Thesis presented in fulfilment of the requirements for the degree of
Master of Engineering (Research) in the Faculty of Engineering, Department of Civil
Engineering at
Stellenbosch University

Supervisor: Professor Kim J. Jenkins

SANRAL Chair in Pavement Engineering

December 2014

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DECLARATION

By submitting this thesis electronically, I declare that the entirety of the work contained therein
is my own, original work, that I am the sole author thereof (save to the extent explicitly
otherwise stated), that reproduction and publication thereof by Stellenbosch University will not
infringe any third party rights and that I have not previously in its entirety or in part submitted it
for obtaining any qualification.

December 2014
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ABSTRACT
Flexible pavement designers have a choice of two wearing course: either asphalt concrete or surfacing
seals. The latter have been widely used by several countries as their preferred wearing course over
other methods, especially countries with a limited number of average inhabitants per square kilometre.
Moreover, the surfacing seals were identified as an efficient cost effective road preventive
maintenance technique. Surfacing seals in New Zealand, South Africa and Australia cover about 65%,
80% and 90% of their surfaced road networks respectively. The preference of surfacing seals is due to
their competitive initial cost and ease of construction.
In South Africa, the life expectancy of surfacing seals varies between 8 and 12 years with an average
of 10 years. This has not been the case in a number of surfacing seals constructed in winter, especially
when the night recorded temperature is below 10oC. The dominant failure mechanism is ravelling
(chip loss) soon after construction due to traffic loading. This chip loss is linked to the poor adhesion
bond development rate in the bitumen-aggregate system during winter adverse conditions. In order to
address the issue of premature chip loss the need for the development of a robust adhesion test method
was identified. For that purpose, recently, researchers in the bitumen industry developed the Bitumen
Bond Strength test method. This method was used in this study.
This study intends to contribute to the understanding of binder-aggregate adhesion bond development
for winter surfacing seals using the BBS test. Binder type, precoat type and conditioning, aggregate
type and curing time are amongst the factors influencing winter seals adhesion bond performance. An
experimental matrix involving three types of binder, two types of aggregate, four different precoating
fluids, two precoat conditionings and two binder-curing times were then developed and investigated.
Winter weather parameters affecting adhesion properties were also taken into consideration during the
course of the investigation. Throughout the test, the procedure described in AASHTO TP 91-11 was
followed. However, in order to enhance the control of the binder application temperature, a new
method for hot applied binder sample preparation was developed as part of this study.
The findings show that there is a significant difference between adhesion properties of the hot applied
binders (70/100 and S-E1) and the emulsion (SC-E1). In most of the cases, the hot applied binders
performed better than the emulsion. The failure mode observed was found to be linked to the
condition of the precoating. The influence of the precoat type and conditioning, and effect of binder
curing time were significantly highlighted. The use of a dry precoat benefited the adhesion bond
strength up to around 50% relatively to the corresponding non-precoated combination. However, a
decrement in the bond strength due to precoating of up to 28.7% was also observed.
A statistical analysis using ANOVA did not illustrate any statistical significant effect of the aggregate
type. The interaction effects analysis using ANOVA revealed the aggregate type interacting with
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precoat type to be the most influential interaction at level two. The precoat conditioning implication to
the adhesion development rate, which influences the time for opening to traffic after construction, was
illustrated. Insightful aspects on the compatibility between the binder type and precoat type and
conditioning during the aggregate precoating practices and on the time for opening to traffic are
highlighted. Finally, the repeatability analysis proved the BBS test to be a repeatable testing method
with caution. Recommendations for further studies that could support the conclusions drawn in this
study were provided.

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OPSOMMING
Buigbare plaveiselontwerpers het 'n keuse van twee deklae: óf Asfalt of oppervlak seëls.
Laasgenoemde word algemeen gebruik deur verskeie lande as hul voorkeur deklaag, veral die lande
met beperkte aantal gemiddelde inwoners per vierkante kilometer. Verder, is die seëls geïdentifiseer
as 'n doeltreffende koste-effektiewe deklaag tegniek. Oppervlakseëls in Nieu-Seeland, Suid-Afrika en
Australië dek ongeveer 65%, 80% en 90% van hul padnetwerke onderskeidelik. Die seëls se voorkeur
is te danke aan hul mededingende aanvanklike koste en eenvoudige vorm van die konstruksie.
In Suid-Afrika wissel die seël se lewensverwagting tussen 8 en 12 jaar met 'n gemiddeld van 10 jaar.
Dit is egter nie die geval van 'n aantal seëls wat in die winter gebou word nie, veral wanneer die
aangetekende nagtemperatuur onder 10o C daal nie. Die dominante swigtingsmeganisme is stroping
(klipverlies) kort na konstruksie. Hierdie klipverlies is gekoppel aan die power kleef-ontwikkeling
van bitumen gedurende die winter. Ten einde die probleem van voortydige klipverlies aan te spreek
het die behoefte vir die ontwikkeling van 'n robuuste toetsmetode ontstaan. Om hierdie rede het
navorsers onlangs in die bitumenbedryf die “BBS toetsmetode” ontwikkel en is dié toetsmetode in
hierdie studie gebruik.
Hierdie studie beoog om by te dra tot die begrip van bindmiddel-klip kleefontwikkeling vir die winter
seëls dmv die BBS toets. Die faktore, insluitend maar nie beperk tot bindmiddeltipe, voorafdekking
(“PRECOAT”) -tipe en kondisionering, aggregaattipe en kuurtyd beïnvloed winter seëls se
kleefeienskappe. 'n Eksperimentele matriks met drie tipes bindmiddels, twee tipes aggregate, vier
verskillende voorafdekking-vloeistowwe, twee voorafdekking kondisionering en twee bindmiddel
kuurtye is toe ontwikkel en ondersoek. Winter weer parameters wat kleefeienskappe beïnvloed is ook
in ag geneem tydens die verloop van die ondersoek. Regdeur die studie is die prosedure AASHTO
TP 91-11 gevolg, maar ten einde die beheer van die bindmiddel spuittemperatuur te verbeter, is ‘n
nuwe metode vir warmspuit-bindmonsters voorbereiding ontwikkel as deel van hierdie studie.
Die bevindinge toon dat daar 'n beduidende verskil tussen die kleefeienskappe van die warm
aangewende bindmiddels (70/100 en S-E1) en die emulsie (SC-E1) is. In die meeste van die gevalle
het die warmspuit-bindmiddels beter as emulsie gevaar. Daar is gevind dat die swigtingsmeganisme
verbind word met die toestand van die voorafdekking. Die invloed van voorafdekkingtipe,
kondisionering, en die effek van bindmiddelkuurtyd is duidelik uitgelig. Die gebruik van droë
voorafdekking het die kleefkrag tot sowat 50% verhoog relatief tot die ooreenstemmende onbedekte
klipkombinasie. Daar is egter ook ‘n verlaging van die kleefkrag weens voorafdekking gevind van tot
so hoog soos 28,7 persent.
Die statistiese ontleding met behulp van ANOVA het geen statisties beduidende effek van die
verksillende aggregaattipe te vore gebring nie. Die interaksie-effek analise, met behulp van ANOVA,
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het wel die interaksie met voorafdekkingtipe met aggregaat die mees invloedryke bevestig. Die
voorafdekking kondisioneering het ver rykende kleefkrag implikasies bloot gelê, wat die tyd vir die
opening van die verkeer na konstruksie beïnvloed. Insigwekkende aspekte oor die versoenbaarheid
tussen die bindmiddeltipe, voorafdekkingtipe, kondisionering, voorafdekkingpraktyk en tyd tot
opening vir verkeer word uitgelig. Ten slotte, die herhaalbaarheidsanalise het die BBS toets as 'n
herhaalbare toetsmetode met omsigtigheid bewys. Daar is aanbevelings tot verdere studies, wat uit
die gevolgtrekking gekom het, gemaak.

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ACKNOWLEDGMENTS
At the end of this study, I am very grateful to the Almighty Father my Lord, He who provided me
with health, endurance and blessings during this period of studies. You have paved my way for this
study in a very mysterious way and through your grace; different people came into play.
I would like to express my sincere and special gratitude and appreciation to my mentor and supervisor
Professor Kim J. Jenkins. Kim did not only accept to involve me in his research team but he also
introduced me to Stellenbosch University. Without your support and assistance, my effort would have
amounted to nothing. Your trust, support, guidance and advices are highly appreciated.
I wish also to express my gratitude to the following persons who have contributed, one way or the
other, to the successful completion of this study:
 Chantal Rudman (Stellenbosch University): Your unwonted kindness and invaluable
assistance contributed to the successful completion of these studies and are highly
appreciated
 Kobus Louw (Colas-South Africa), your contribution to the successful completion of this
study is invaluable. From material sourcing and supply to results interpretation, your helpful
and thought-provoking discussions, and timely assistance are highly acknowledged.
 Prof. Martin Van de Ven (TU Delft), your kindness and willingness to share knowledge
inspired me. Your innovative and helpful ideas are greatly appreciated.
 Johan Gerber (PhD-Student Stellenbosch), your assistance and help for the rock roughness
analysis to be possible is highly acknowledged.
 Estimé Mukandila (PhD student, University of Pretoria): your kindness, trust and flexibility
to offer your research material for the interest of this research is highly appreciated.
 Alex Mbaraga Ndiku, I thank you for your interesting discussions that helped me to stimulate
and solidify my thinking on many aspects of this research.
 Dr Gibson Ncube, Mr Tinashe Tendai and Mr Fabrice Barisanga, your assistance in thesis
proof reading has put this thesis on a level it was not supposed to reach without your input.
Especially Dr Gibson your tireless assistance is highly acknowledged.
 Mr Riaan Briedehann (Lab Manager), Janine Myburgh, Collin Isaac, Gavin Williams and
Dion Viljion your quick assistance in different ways are highly acknowledged.
 Hanlie Botha (Stellenbosch University-Processing Engineering), I am thankful for your help
with ultrasonic cleaner.
 Maggie Goosen your assistance to ensure that we are settled for the first time in Stellenbosch
contributed strongly in the successful completion of this study
 Association of Rwandan Students in Stellenbosch members, your friendship and kindness are
appreciated.
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 Officemates, colleagues and friends for your encouragements
I would like also to express my appreciation to some contributing institutions:
I gratefully acknowledge the role the Government of Rwanda through Rwanda Education Board and
the University of Rwanda (College of Science and Technology) played in the successful completion
of this research. Without your financial support, my dreams could not be turned into reality.
I appreciate the assistance of CSIR-Pretoria for aggregate core roughness laser scanning analysis.
Especially the effort, kindness and timely assistance of Dr Joseph Anochie-Boateng are highly
acknowledged.
I finally acknowledge the support and help of my family. Your love, encouragement and prayers
carried me through this time.

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TO MY FAMILY

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TABLE OF CONTENTS
DECLARATION.................................................................................................................................... i
ABSTRACT ........................................................................................................................................... ii
ACKNOWLEDGMENTS ................................................................................................................... vi
DEDICATION...................................................................................................................................... vi
TABLE OF CONTENTS .................................................................................................................... ix
LIST OF FIGURES ............................................................................................................................. xi
LIST OF TABLES ............................................................................................................................. xiv
LIST OF ABBREVIATIONS AND SYMBOLS .............................................................................. xv
ABBREVIATIONS .......................................................................................................................... xv
SYMBOLS ....................................................................................................................................... xvi
CHAPTER 1 INTRODUCTION ........................................................................................................ 1
1.1 BACKGROUND .................................................................................................................... 1
1.2 PROBLEM STATEMENT ..................................................................................................... 4
1.3 RESEARCH OBJECTIVES AND SCOPE ............................................................................ 5
1.4 THESIS OUTLINE ................................................................................................................. 6
CHAPTER 2 LITERATURE REVIEW ........................................................................................... 7
2.1 INTRODUCTION .................................................................................................................. 7
PART A: BITUMEN-AGGREGATE SYSTEM ADHESION BOND DEVELOPMENT ................ 8
2.2 MATERIAL PROPERTIES INFLUENCING ADHESION BOND DEVELOPMENT........ 8
2.3 ADHESION BOND THEORIES AND MECHANISMS .................................................... 35
2.4 SOUTH AFRICAN CLIMATIC CONDITIONS ................................................................. 41
PART B: ROAD SURFACING SEALS .......................................................................................... 44
2.5 SURFACING SEALS ........................................................................................................... 44
PART C: ADHESION TESTING METHODS ................................................................................ 57
2.6 PRACTICAL ADHESION TESTING METHODS ............................................................. 57
CHAPTER 3 RESEARCH METHODOLOGY ............................................................................... 63
3.1 INTRODUCTION ................................................................................................................ 63
3.2 MATERIALS ........................................................................................................................ 64
3.3 EXPERIMENTAL DESIGN ................................................................................................ 67
3.4 BBS TESTING METHOD ................................................................................................... 69
3.5 SPECIMEN PREPARATION .............................................................................................. 70
3.6 BBS TESTING PROCEDURE ............................................................................................. 82
3.7 CONCLUSIONS ................................................................................................................... 87

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